The Periodic Table

1. The Periodic Table Stuff you need to know

2. Periodic Table • In 1869 the Russian chemist Dmitri Mendeleev and the German chemist J. Lothar Meyer, working independently, found that when the elements were arranged in order of atomic weight they could place them in horizontal rows (one under another), so that the elements in each vertical column had similar properties

3. It was shown in the early part of last century (1900s) that the elements are characterized by their atomic numbers, rather than their atomic weights. The modern periodic table lists the atomic number, atomic symbol, and atomic weight of each element

5. THE PERIODIC TABLE

6. Elements • Elements are the building materials for the construction of all living and nonliving things. There are only about 110 types of elements, yet their atoms can join in in almost limitless combinations and proportions.

7. In general • In general, you notice that up to and including atomic # 20, the # of neutrons is pretty much equal to the # of protons. • After element # 20, the # of neutrons exceeds the # of protons, this is because neutrons act as the “glue” to hold the nucleus together and it takes more glue after element # 20. • After element # 83, no amount of neutrons can hold the nucleus together – they are all radioactive. The nucleus decays!

8. Groups • Elements in the same group have similar chemical and physical properties!! • (Mendeleev did that on purpose.) • Why?? • They have the same number of valence electrons. • They will form the same kinds of ions.

9. Group A elements • Each column of elements in the periodic table is known as a group. • Each group is designated by a number-letter combination. • The first column on the left side is designated Group 1A, the one next to it is Group 2A. • All group A elements are known as representative elements.

10. Families • Columns are also grouped into families. • Families may be one column, or several columns put together. • Families have names rather than numbers

11. Hydrogen • Hydrogen belongs to a family of its own. • Hydrogen is a diatomic, reactive gas. • Hydrogen was involved in the explosion of the Hindenberg. • Hydrogen is promising as an alternative fuel source for automobiles

12. Metals • The elements on the left side of the periodic table are metals. • Metals are elements that have a high electrical conductivity, and a high luster when cleaned. • They are ductile and malleable. • Approximately 80% of all elements are metals. Easily lose electrons • Corrode easily. Corrosion is a gradual wearing away. (Example: silver tarnishing and iron rusting)

14. Groups of Metals • With one exception (mercury) metallic elements are solids at room temperature. • The metals in Group 1A are called the alkali metals. • Group 2A is called the alkaline earth metals. • Groups 3B thru 2B (or 3 thru 12) are called the transition metals.

15. The metallic elements between Group 2B and the zig zag line are called other metals. • The metals by themselves at the bottom of the periodic table are called the inner transition metals. These are also called the rare earth metals. These metals are placed at the bottom of the table to shorten the periodic table’s length.

17. The Alkali Metals • The alkali metals are the most reactive metals known. Their reactivity increase as you go down the group. • Alkali metals are not found free in nature, but are combined with nonmetals to form salts. • They react violently with water producing hydrogen gas. This reaction is so rapid and exothermic that the hydrogen often burns as it is produced.

18. The alkali metals have low densities, low melting points, and have electrical conductivity. • They are soft enough to be cut with a knife. • Alkali metals must be stored under mineral oil so as not to react with moisture in the air.

21. Alkaline Earth Metals • The sea is a rich source of magnesium and calcium ions. Shellfish use calcium to build their calcium carbonate shells. • They are extracted from mineral ores that in early times were called “earths”. • They are less reactive than the alkali metals and harder.

23. Transition Metals • With the exception of copper and gold, transition metals have a silvery luster. • The transition metals vary greatly in their chemical reactivity. • Copper, silver, and gold have low chemical reactivity and often occur naturally in the free state. Copper is the most widely used metal for electrical wiring. Only silver is a better conductor of electricity.

24. Transition Metals • Less reactive harder metals • Includes metals used in jewelry and construction